Enhanced dissolved oxygen groundwater remediation method and system

ABSTRACT

A bioremediation method and system for destroying or reducing the level of contaminants in a contaminated subterranean body of water includes a plurality of injection sites. The injection sites extend below ground and intersect a body of groundwater. Each of the plurality of injection sites are in communication with a supply of concentrated oxygen. Each of the plurality of injection sites are also in communication with a supply of microbials. The oxygen is conveyed by a delivery mechanism from the supply of oxygen to the injection points. The microbials are also conveyed to the injection points to naturally reduce the contaminants in the groundwater.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present invention claims priority from U.S. ProvisionalApplication No. 60/296,540, entitled “Direct Oxygen Injection TechnologySystems”, filed Jun. 6, 2001 and U.S. Provisional Application Serial No.60/296,528, entitled “Enhanced Dissolved Oxygen Technology Systems”,filed Jun. 6, 2001.

TECHNICAL FIELD

[0002] The present invention relates generally to a method and systemfor reducing the level of contaminants in a body of groundwater and moreparticularly to a bioremediation method and system for groundwatertreatment that utilizes biodegraders.

BACKGROUND ART

[0003] Groundwater contamination, typically arising from petroleumstorage tank spills or from intentional or accidental discharge ofliquid hydrocarbons or compositions containing same, has become aproblem of increasing concern. This type of contamination occurs notonly at industrial complexes, but also in suburban neighborhoods, whichwould appear to be havens from such phenomena. The source ofcontamination in suburban neighborhoods or areas is very commonlyautomobile service station sites at which antiquated or abandonedstorage tanks have released gasoline, fuel oils, lubricants, and thelike into the local groundwater. Other common sources of such noxiousmaterials can include dry cleaning establishments and/or manufacturersor distributors of the tetrachloroethane which is used in the drycleaning process.

[0004] Various remediation techniques have been utilized in the past forthe treatment of contaminated groundwater in order to reduce oreliminate the contaminants, such as COCs. One of the most widely usedsystems is one based on so-called “pump and treat” technology. Thesesystems withdraw the contaminated groundwater and a phase-separatedproduct from a recovery well located in the groundwater and pump it toan above ground treatment facility. Thereafter, various treatmenttechniques, as are well known, are used to remove contaminants from thedisplaced groundwater. These “pump and treat” systems are relativelyexpensive to install and require that the remaining contaminants, whichhave been separated from the groundwater, be disposed in anenvironmentally friendly manner. These processes further increase thecost of the techniques.

[0005] One example of a known remediation system is disclosed in U.S.Pat. No. 5,286,141. The '141 patent teaches oxidizing the source ofgroundwater contamination to harmless constituents by locating aplurality of mutually spaced wells into a groundwater region. A treatingflow of hydrogen peroxide solution is provided into the groundwater fromone or more wells. The treating flow typically contains reaction surfaceenhancing reagents, which provide increased surfaces at which thereaction between the hydrogen peroxide and the hydrocarbon contaminantsmay occur. Further, a catalytic agent is also preferably incorporatedinto the treating solution or as a pre-injection into the groundwaterregion to promote the desired reaction between the hydrogen peroxide andhydrocarbons.

[0006] Recently, there has also been increasing interest inbioremediation technology. However, its use in treating groundwater hasbeen relatively ineffective due to the complexity of the procedures andequipment required, including expensive and complex reactors. Moreover,current bioremediation techniques can cause adverse geochemicalreactions and can introduce new toxic compounds into the groundwater.Additionally, current bioremediation systems, still require the use ofnon-organic catalysts or additives to cause the process to be completedin a reasonable period of time. These catalysts or additives raise othercontaminant issues with respect to the groundwater.

[0007] It is known that naturally growing bacteria in the groundwatercan break down groundwater contaminants. However, these bacteria are notalways present in large enough quantities to be effective and can alsobe absent altogether. Moreover, these bacteria feed off oxygen and thelack of oxygen is the single biggest limiting factor on the growth ofthe bacterial population and therefore contaminant decrease. Ambientair, which is comprised of about 21% percent oxygen, only results inapproximately 10-12 ppm of dissolved oxygen in the groundwater and thusis not sufficient to adequately destroy or reduce contaminants. Variousattempts to increase the amount of oxygen by utilizing oxygen releasingcompounds have been tried, but these oxygen releasing compounds, such asmagnesium peroxide or calcium peroxide are expensive. Further, theseoxygen releasing compounds only produce a small amount of usable oxygenand therefore do not significantly increase the bacterial population.

SUMMARY OF THE INVENTION

[0008] It is therefore an object of the present invention to provide abioremediation method and system for groundwater treatment that is moreeffective than prior bioremediation systems.

[0009] It is another object of the present invention to provide abioremediation method and system for groundwater treatment that is lessexpensive than prior bioremediation systems.

[0010] It is still another object of the present invention to provide abioremediation method and system for groundwater treatment that treatscontamination naturally and effectively.

[0011] It is still another object of the present invention to provide abioremediation system that is relatively easy and inexpensive to installand operate.

[0012] It is a related object of the present invention to provide abioremediation system that can be installed with minimal sitedisturbance.

[0013] In accordance with the above and other objects of the presentinvention a bioremediation method and system is provided. The methodincludes providing a plurality of injection points extending from aboveground to a subterranean body of groundwater. A source of substantiallypure oxygen is provided. A supply of microbials is also provided. Theoxygen and an amount of microbials are each delivered to the pluralityof injection points and into the subterranean body of groundwater untilthe level of contaminants in the groundwater is reduced or eliminated.

[0014] The system includes a plurality of injection points extendingbelow ground such that they intersect a body of groundwater. The systemincludes a supply of concentrated oxygen and a supply of microbials. Theoxygen and microbials are each delivered to the plurality of injectionpoints and into the groundwater.

[0015] The above objects and other objects, features and advantages ofthe present invention will be apparent from the following detaileddescription of best made for carrying out the invention to be taken inconnection with the accompanying drawings and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a schematic illustration of an enhanced dissolved oxygengroundwater bioremediation system in accordance with a preferredembodiment of the present invention;

[0017]FIG. 2 is a schematic illustration of the breakdown ofcontaminants in accordance with a preferred embodiment of the presentinvention; and

[0018]FIG. 3 is an illustration of a flow meter of the system of FIG. 1in accordance with a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0019] Referring now to FIG. 1 which illustrates a bioremediation system10 in accordance with the present invention. The preferredbioremediation system 10 is preferably used to clean up biodegradablepetroleum constituents that are present in contaminated groundwater.However, it should be understood, that the system 10 can be used toclean up other contaminates or constituents in groundwater and that thesystem may be used for a variety of other purposes.

[0020] The preferred bioremediation system 10 preferably includes asource of oxygen 12, such as a liquid oxygen tank. However, the oxygencan be provided in a variety of other forms. While the source of oxygenis preferably pure, it can also be of sufficient purity to accomplishthe objectives of the present invention. For example, a source of oxygenthat has over 50% oxygen may also be sufficient. The source of oxygen 12is preferably in communication with a control panel 14 to regulate theflow of oxygen from the oxygen source 12. The oxygen that flows to thecontrol panel 14 is then conveyed to a plurality of injection sites 16in a subterranean body of groundwater, generally indicated by referencenumber 18. The plurality of injection sites 16 are also in communicationwith a supply of microbials 20. The location of the injection sites 16can be determined in a variety of ways, as discussed below.

[0021] The source of oxygen 12 is preferably coupled to the controlpanel 14 by a pressure hose 22 in order to convey the oxygen thereto.The pressure hose 22 has a first end 24 that is connected to the sourceof oxygen 12 and a second end 26 that is connected to the control panel14. The source of oxygen 12 has a shut off valve 28 associated therewithwhich is located between the source of oxygen 12 and the first end 24 ofthe pressure hose 22. The shut off valve 28 allows the flow of oxygenfrom the source of oxygen 12 to the pressure hose 22 to be manuallyclosed as desired. It should be understood that the valve 28 can also beelectronically controlled. The second end 26 is preferably connected toa pressure regulator 30 which allows the pressure of oxygen exiting thesource of oxygen 12 to be controlled. In the preferred embodiment, thepressure regulator 30 is set such that the pressure of oxygen exitingthe oxygen source 12 is set for example, at 100 psi. It should beunderstood that the pressure regulator 30 can be adjusted to regulatethe flow of oxygen to a variety of different pressures.

[0022] The oxygen that exits the pressure regulator 30 enters a firstconduit 32, which conveys the pressure regulated oxygen to an oxygenheader pipe 34. The oxygen header pipe 34 has a plurality of flow meters36 connected thereto and in fluid communication therewith. The pressureregulator 30, the first conduit 32, the oxygen header pipe 34, and theplurality of flow meters 36 are all preferably disposed within thecontrol panel 14 and the control panel 14 is preferably mounted to afence, wall or other structure 38. However, more or less items may beincluded in the control panel 14. The flow meters 36 regulate the flowof oxygen from the header pipe 34 to a respective outlet tube 40. Theoutlet tube 40 is also in communication with a source of microbials 42through a microbial outlet tube 44. The microbials 42 exit the source 42and pass through the microbial outlet tube 44 and enter the outlet tubes40. Preferably, the microbials 42 are injected initially prior toinjection of the oxygen. The amount of microbials is preferablydetermined based on the size of the contaminated area. Thereafter, themicrobials will reproduce to ensure that an appropriate amount of foodfor the oxygen is present in the groundwater.

[0023] The outlet tube 40 is in communication with an injection tube 46that terminates at a respective one of the plurality of injection sitesor points 16. Accordingly, the number of flow meters 36 that areutilized in a particular system will depend upon the number of injectionsites that are determined to be necessary to clean up the groundwater ata given location. The conduits, pipes, tubes, and injection points arepreferably constructed of PVC piping. The outlet tube 40 is preferably ¼inch tubing and the injection tubes 46 are preferably ½ inch tubing. Thesize and material of the pipes and tubes can obviously vary.

[0024] Referring now to FIG. 2, which illustrates the desired chemicalreaction induced by the preferred bioremediation system 10. As shown, acontaminant is present in the groundwater 18, as generally indicated byreference number 48. Oxygen molecules, as generally indicated byreference number 50, are fed to a microbial, which is generallyindicated by reference number 52. The microbial 52 feeds off the oxygenmolecules 50 and breaks down the contaminants 48 into a combination ofwater, as generally indicated by reference number 54, and carbondioxide, as generally indicated by reference number 58. It will beunderstood that the contaminants are typically a COC chain, but could bea variety of other contaminants that require removal.

[0025] The system 10 is preferably installed at a site that was formerlya service station and has been determined to have groundwater that iscontaminated with petroleum, whether through accidental or intentionalspillage. As is known, the groundwater can be tested through the use ofa monitoring well to determine whether or not the groundwater has beencontaminated. In accordance with the present invention, one way fordetermining the existence of contaminants is the absence or depletion ofoxygen which indicates that naturally existing bacteria are feeding onthe oxygen in an effort to breakdown the contaminants. It can be assumedthat a body of groundwater has unacceptable levels of contamination whenthe percentage of oxygen in and around the groundwater is in the orderof 0%-1%.

[0026] Once it has been determined that the groundwater is contaminated,in accordance with the present invention, the location of the injectionpoints can be determined. The location of the injection points can bedetermined in a variety of different methods. Preferably, however, theinjection points are located in a grid that takes into account thedirection and flow rate of groundwater flow. By taking into account thegroundwater flow, injection sites will be positioned to preventcontaminants from spreading. Typical grid determination is based on sitespecifics, but generally, a grid is based on two months of groundwaterflow (e.g. if the groundwater flows 120 feet per year, the grid would bea 20 foot grid).

[0027] A plurality of monitoring wells 66 are preferably utilized todetermine the extent and location of any contaminants so that the systemusage can be maximized. Obviously, any number of wells can be created.The injection sites 16 are preferably located in a grid pattern as shown(i.e. columns and rows), and then the injection tubes 46, which areconnected to the source of liquid oxygen 12 and the control panel 14 andalso the source of microbials 42 are installed to inject the pure oxygeninto the groundwater at the injection sites 16.

[0028] Once the system is installed, the oxygen vapor will be regulatedand metered to be delivered into the groundwater at a predeterminedrate. The rate is preferably adjusted over time. The dissolved oxygen inthe groundwater and the amount of oxygen in the soil gas are monitoredto assure a sufficient flow of oxygen to the injection sites 16.Similarly, the oxygen is monitored to determine if too much oxygen isbeing added in order to prevent undue waste. Obviously, the rate andpressure of the oxygen vapor can be varied as needed. The effect of thesystem on the contaminants can be monitored periodically through themonitoring wells. Further, if the source of oxygen 12 becomes depleted,it can be easily replaced without disrupting the clean up process.Additionally, if the source of microbials 12 becomes depleted, it canalso be easily replaced without disrupting the remediation process.

[0029] The preferred system is relatively inexpensive to install as itcosts significantly less than prior systems. Moreover, the systemoperates twenty-four hours a day and requires no electricity ormaintenance to operate. Further, as there are no moving parts, there isnothing to lube, oil or grease. The system is also less susceptible tobreak down.

[0030] It has been determined that pure oxygen works to clean upcontaminants in a body of groundwater more efficiently than ambient airand more efficiently and at less cost than various oxygen releasingcompounds. By increasing the amount of dissolved oxygen, it has beenfound that the bacterial population increases by over a magnitude of athousand. However, if the bacterial population is too small ornonexistent, it needs to be enhanced for the pure oxygen to workeffectively. The issue thus becomes how to deliver the pure oxygen andthe microbials into the ground and into communication with thegroundwater. In accordance with the present invention, the preferred wayis through the delivery system described above. Moreover, other deliverysystems for conveying the oxygen and microbials to the injection sitesmay also be utilized.

[0031] However, in the preferred embodiment, a plurality of injectiontubes 46 are utilized to convey the pure oxygen from the source 12 andmicrobials from the source 42 to the injection sites 16. While thesource of oxygen 12 is preferably initially in liquid form, the pressurein the source 12 causes the liquid to turn to vapor. It is the pureoxygen vapor that is captured and then delivered through the deliverysystem and reacts with the microbials. The injection points 16 and theinjection tubes 46 can be installed by any of a variety of methods,including typical hollow stem auger with sand backfill. This isprimarily for sites interbedded with clays and sites. Alternatively, theinjection tubes 38 may be installed by known GeoProbee® (GeoProbe is aregistered trademark of KEJR Engineering, Inc. of Kansas) installationtechniques.

[0032] Preferably, the injection tubes 46 are installed by airjetinjection. Airjet injection is a novel installation technique that ispart of the present invention. In accordance with the present invention,airjet injection utilizes a compressor that is connected to an injectiontube 46 via a hose. The air flow and pressure from the compressor act asa cutting tool and the injection tube 46 can be “injected” or insertedinto the ground with minimal site description and minimal time andcapital expense. It has been determined that up to eighty (80) or moreinjection points can be installed in a single day. This is significantlyhigher than the number of points that could be installed under priorinstallation methods.

[0033] As shown in more detail in FIG. 3, each flow meter 36 ispreferably connected to the oxygen header pipe 34 by a compressionfitting 60 that allows oxygen at the regulated pressure to be deliveredthereto. Each flow meter 36 is preferably mounted to a mounting board 62or other structure in the control panel 14 and includes a pressureindicator 64 that provides a visual indication of the pressure of fluidflowing therethrough. The outlet tubes 40 that are in communication withthe outlet of the flow meters 36 preferably extend through a protectiveconduit 64 (FIG. 1) which extends from the control panel 14 into theground. The protective conduit 64 acts to shield and protect the outletpiping 40. The outlet piping 40 is preferably located at least one footbelow the ground and runs generally parallel thereto. The injectiontubes 46 are in communication with the outlet piping 40 and extendgenerally perpendicularly downward from the outlet piping 40. As shown,the outlet piping 40 intersects the groundwater 18 below the water tableat designated injection sites 16 in order to deliver the pure oxygen andthe microbials thereto.

[0034] While particular embodiments of the invention have been shown anddescribed, numerous variations and alternate embodiments will occur tothose skilled in the art. Accordingly, it is intended that the inventionbe limited only in terms of the appended claims.

In the claims:
 1. A method for remediating a contaminated region of asubterranean body of groundwater to destroy or reduce the initialconcentration levels of contaminants, comprising: providing at least oneinjection point extending from above ground to the subterranean body ofgroundwater; delivering substantially pure oxygen to said at least oneinjection point and into the subterranean body of groundwater; anddelivering an amount of microbials to said at least one injection pointand into the subterranean body of groundwater to assist in reducing thelevel of contaminants.
 2. The method of claim 1, further comprising:providing a plurality of injection points extending from above ground tothe subterranean body of groundwater.
 3. The method of claim 2, furthercomprising: providing a supply of oxygen in communication with each saidplurality of wells.
 4. The method of claim 3, further comprising:regulating the flow of oxygen from said supply of oxygen to saidplurality of injection points.
 5. The method of claim 2, wherein saidplurality of injection points are arranged in a grid pattern.
 6. Themethod of claim 3, wherein said supply of oxygen is in liquid form. 7.The method of claim 6, further comprising: converting said liquid oxygento oxygen vapor.
 8. The method of claim 1, further comprising:installing said at least one injection point through GeoProbeinstallation techniques.
 9. The method of claim 1, further comprising:installing said at least one injection point through airjet installationtechniques.
 10. A system for naturally remediating a contaminatedsubterranean body of groundwater to destroy or reduce the levels ofcontaminants, comprising: a plurality of injection points extendingbelow ground to intersect the body of groundwater; a supply ofconcentrated oxygen in communication with each of said plurality ofinjection sites; a supply of microbials in communication with each ofsaid plurality of injection sites; and a mechanism for conveying saidconcentrated oxygen and said microbials to each of said plurality ofinjection points.
 11. The system of claim 10, wherein said supply ofconcentrated oxygen is in liquid form.
 12. The system of claim 10further comprising: a control panel interposed between said supply ofconcentrated oxygen and said mechanism for conveying said concentratedoxygen to each of said plurality of injection points to regulate theflow of oxygen.
 13. The system of claim 12, wherein said control panelincludes a plurality of flow meters for regulating the flow rate ofoxygen to said plurality of injection points.
 14. The system of claim10, wherein said mechanism includes a plurality of plastic tubes forconveying said concentrated oxygen to said plurality of injectionpoints.
 15. A method for remediating contaminated groundwater,comprising: providing a supply of oxygen; removing oxygen from saidsupply of oxygen; regulating the pressure of said removed oxygen;injecting said oxygen into the groundwater; and providing a supply ofmicrobials; and injecting an amount of microbials from said supply ofmicrobials into the groundwater.
 16. The method of claim 15, whereinsaid supply of oxygen is in liquid form.
 17. The method of claim 16,wherein said removed oxygen is in vapor form.
 18. The method of claim15, further comprising: regulating the flow rate of said oxygen injectedinto said groundwater.
 19. The method of claim 18, further comprising:monitoring the levels of oxygen in the groundwater to determine whetherthe flow rate of oxygen needs adjustment.